Filter silencer units are often installed upon a tractor for a pneumatic operative tank trailer. This is a tank trailer which unloads its cargo under the influence of moving pressurized air, as when it arrives at the site of delivery.
Pipes or hopper tee's on railroad tank cars, tank trailers, pipelines, and other means for conveyance have been available for some time. The delivered product exits from the storage compartment of the transport carrier, such as its tank trailer, and then flows through piping upon the trailer for delivery by hose or further piping to a storage facility or location of usage. In dry bulk hauling, such as of pellets, powders, and grains, the seal integrity at the pipe connection is essential to prevent contamination of the material either to be hauled, or after hauling, such as in a tank trailer, and it is desirable to provide not only cleansed air that is used in the unloading process, but also to reduce the volume of noise involved in the discharge, when accomplished. The pellets or powders unloaded from the gravity gate valves or hoppers located on the bottom of the tank car, exit through tee's that are attached to the bottom of a hopper which normally connect with a collection of pipes, that convey air under pressure to assist in the unloading process. A vacuum or air stream from a pneumatic conveyor system created in the piping system accelerates the unloading of dry bulk products from a hopper. This is known in the art.
During the unloading process, the hopper of the tank trailer must be completely empty, and all of the dry bulk product removed, to prevent contamination of any later loads. In addition, not only must the unloading air pressure system be 100% effective in removing the transported cargo, but it is highly necessary that the air itself be reasonably purified, so as not to add any contamination to the discharging bulk granular material, during unloading. Any residue that remains may contaminate subsequent loads, or may generate any mold or other deleterious substance, that can contaminate subsequent loads, as aforesaid.
Presently, the bulk transporting industry favors downloading dry product from tank trailers by pneumatic systems. This can be seen in U.S. Pat. No. 7,520,925, for which the inventor of this current application was a co-inventor therein. A pneumatic system begins with a blower mounted to a tractor, often a truck. When turning at high revolutions per minute, the blower forces air into a discharge pipe that pressurizes the collection pipes below a trailer. The pressurized air then attracts by venturi flow the granular material, by gravity out of the tank trailer, and it is conveyed within the stream of the pressurized flowing air, to the site of storage. The pressurized air then delivers the dry bulk product from the collection pipes to the delivery point, commonly by way of a hose. As known, a typical blower generates much noise, and permits traces of oil, grease, and dirt to enter the discharge pipe. All of these are detrimental. As mentioned above, contamination remains of high concern to dry bulk haulers, particularly where the cargo may be subsequently used in food stuffs, or as ingredients therefore. During downloading of dry bulk products, contamination must be lowered, if not eliminated, in ordered to meet food safety standards. In addition, any noise levels generated during unloading must be lowered generally to conform with local noise ordinances.
Other examples of prior filtration or fluid conveying systems can be seen in the United States Patent to Wiltse, U.S. Pat. No. 2,897,005, that shows a fluidize pressure system.
The patent to Wachter, U.S. Pat. No. 3,201,927, discloses a closure device for a filter container. This filter container apparently is used as a gas cleaning filter, and has flow outwardly of the filter, rather than inwardly thereof.
The patent to Rosaen, U.S. Pat. No. 3,295,679, shows a bayonet fluid filtering assembly.
The patent to Perry, U.S. Pat. No. 3,300,050, shows another filter unit, in this instance, used in a fuel dispensing hose.
The patent to Krambrock, U.S. Pat. No. 3,929,379, shows a further method and apparatus for the pneumatic conveying of bulk material. This has been previously described in the background of the invention herein as to how the current invention is utilized for conveying bulk granular material from a tank trailer hopper.
U.S. Pat. No. 4,207,883, to Shindler, discloses a hood assembly with a noise filter.
The patent to Schenker, U.S. Des. 261,501, discloses a combined air muffler and filter.
The patent to Hirschorn, U.S. Pat. No. 4,316,522, discloses an acoustic filter silencer. This appears to be a rather elaborate filtration device for attenuating sound.
U.S. Pat. No. 4,632,682, to Erdmannsdorfer, discloses a cartridge type oil separator air filter.
The patent to Lott, et al, U.S. Pat. No. 4,818,398, discloses a further filter system with readily replaceable filter element.
The patent to Terhune, et al, U.S. Pat. No. 4,871,455, further discloses a filter assembly with lockable lug means.
A further patent to Sisk, U.S. Pat. No. 5,067,856, discloses an inline air filter for dry bulk tank trailers. This is similar to the filter means as described in the previous Sisk '925 patent, and is used in the discharge of bulk granular material from their conveying vehicle.
The patent to Tsuchiya, et al, U.S. Pat. No. 5,653,870, discloses another filter system.
The published application to Buckner, No. U.S. 2003/0234137, shows a vacuum pump filter that has a silencer in combination therewith.
Finally, the published application to Suri, No. U.S. 2005/0178716, discloses a filter assembly with filter element incorporating an integral seal.
The present invention overcomes select limitations of the prior art, and in addition, adds supplemental improvements the efficiency of functioning of the air filtering system, in addition to damping the decibels of any generated sound, during its operations while unloading a tank trailer of its granular material.